1. Field of the Invention
The present invention relates to an improved electrical contact construction for air-blast circuit breakers including a tubular contact and a contact axially associated therewith (also tubular in shape) between which, upon interruption under load, an arc is drawn which is blasted by a stream of compressed gas, and in which each tubular contact has a nozzle at its end face in which a tubular member fabricated of ferromagnetic material is disposed in spaced-apart relationship to the contact.
2. Description of the Prior Art
Contact arrangements of the foregoing type are known in the art. See German Offenlegungsschrift Nos. 27 06 470 and 26 24 595. In such arrangements, the arc produced upon interrupting a current flow through the breaker is driven into the interior of the tubular contacts by the compressed gas blast. The bases of the arc travel towards and reach the tubular members, which are designed as hollow cylinders of ferromagnetic material, inside the contacts, and at that point the magnetic field induced in the tubes contributes to driving the bases of the arc away from the nozzles of the contacts. As a result, the arc bases travel along the inside walls of the tubular members in a direction away from the nozzle members. In this manner, the arc is lengthened and more reliably quenched by the compressed-gas stream blast. It has been found in practice that currents of only up to 80 kA can be switched reliably using such a contact arrangement.